It is known to prepare cyclic sulphates by reaction of sulphuric anhydride with an alkylene oxide, the operation being carried out in dioxane (U.S. Pat. No. 3,045,027) or in another organic solvent such as in dichloroethane (U.S. Pat. No. 3,154,526 or U.S. Pat. No. 3,167,572) or in gaseous phase at a temperature below 140.degree. C. (U.S. Pat. No. 3,100,780). However, these processes do not make it possible to obtain cyclic sulphates in satisfactory yields.